gistfile1.rb

#### image_map_coordinate.rb #### 

class ImageMapCoordinate < ActiveRecord::Base              
  belongs_to :image_map                                    
                                                           
  # FIXME: validation bug?                                 
  %w(w h x y).each do |v|                                  
    validates_numericality_of eval ":#{v}"                 
  end                                                      
  validate :href_validator                                 
                                                           
private                                                    
  def href_validator                                       
    # regex URL validator                                  
    if (self.href =~ URI::regexp).nil?                     
      errors.add(:href, "must be a valid URL")             
    end                                                    
  end                                                      
end


#### image_map.rb ####

class ImageMap < ActiveRecord::Base                         
  belongs_to :plugin                                        
  belongs_to :brand                                         
  has_one :image_map_image, :dependent => :destroy          
  has_many :image_map_coordinates, :dependent => :destroy   
                                                            
  # TODO: Dry this up!                                      
  validates_numericality_of :render_priority                
                                                            
  # enforce has_one relationships                           
  validates :brand_id, :uniqueness => true                  
                                                            
  # ensure brand_id and plugin_id point to existing objects 
  validates_presence_of :plugin                             
  validates_presence_of :brand                              
                                                                                      
end  

#### image_maps_controller.rb ####
...
def update
  @image_map = ImageMap.find(params[:id])
  coords = []
  params[:coords].each do |c|
    coords << ImageMapCoordinate.new(c)
  end
  @image_map.image_map_coordinates = coords
  respond_to do |format|
    if @image_map.update_attributes(params[:image_map])
      format.html { redirect_to edit_brand_url(@image_map.brand), notice: 'plugin was successfully updated.' }
    else
      format.html { render :template => 'plugins/image_map/edit' }
    end
  end 
end
...